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Abstract:

A NodeB for a WCDMA system, arranged to transmit instructions to a UE for
the UE's uplink transmissions. The NodeB is arranged to transmit the
instructions on a dedicated downlink physical channel which the NodeB is
arranged to use for transmissions to a plurality of UEs and which
comprises a plurality of radio frames, where each radio frame comprises a
number of slots and each slot comprises a number of WCDMA symbols. The
instructions to the UE comprise Transmit Power Commands as well as other
instructions to the UE for the UE's uplink transmissions. The NodeB is
arranged to use a first WCDMA slot format for the TPC commands to the UE
and a second WCDMA slot format for the other instructions to the UE.

Claims:

1. A NodeB for a WCDMA system, the NodeB being arranged to transmit
instructions to a UE for the UE's uplink transmissions, the NodeB being
arranged to transmit said instructions on a dedicated downlink physical
channel which the NodeB is arranged to use for transmissions to a
plurality of UEs and which comprises a plurality of radio frames, with
each radio frame comprising a number of slots, each slot comprising a
number of WCDMA symbols, the instructions to the UE comprising Transmit
Power Commands, TPC commands as well as other instructions to the UE for
the UE's uplink transmissions, the NodeB being arranged to use a first
WCDMA slot format for the TPC commands to the UE and a second WCDMA slot
format for the other instructions to the UE.

2. The NodeB of claim 1, being arranged to transmit instructions to more
than one UE in one and the same WCDMA symbol.

3. The NodeB of claim 1, being arranged to transmit said other
instructions to a UE over several slots, using said second WCDMA slot
format.

4. The NodeB of claim 1, being arranged to use said second WCDMA slot
format with a frequency which varies according to the UE's speed of
movement, so that the ratio between the number of slots with TPC and said
other instructions vary adaptively with the UE's speed of movement.

5. The NodeB of claim 1, in which the other instructions to a UE comprise
instructions for uplink beam forming by the UE.

6. The NodeB of claim 1, in which the other instructions to a UE for the
UE's uplink transmissions comprise instructions on the number of MIMO
streams to be used by the UE in uplink MIMO transmissions.

7. The NodeB of claim 1, in which the dedicated downlink physical channel
is the WCDMA F-DPCH channel.

8. A UE for a WCDMA system, the UE being arranged to receive instructions
from a NodeB for uplink transmissions, the UE being arranged to receive
said instructions on a dedicated downlink physical channel which is used
by the NodeB for transmissions to a plurality of UEs and which comprises
a plurality of radio frames, with each radio frame comprising a number of
slots, each slot comprising a number of WCDMA symbols, the UE being
arranged to use a certain slot format to interpret a slot, the
instructions from the NodeB comprising Transmit Power Commands, TPC
commands as well as other instructions for uplink transmissions, the UE
being arranged to use a first WCDMA slot format to locate TPC commands
and a second WCDMA slot format to locate the other instructions.

9. The UE of claim 8, being arranged to receive instructions which
comprise a part of a WCDMA symbol.

10. The UE of claim 8, being arranged to receive said other instructions
over several slots, using said second WCDMA slot format.

11. The UE of claim 8, in which the other instructions from the NodeB
comprise instructions for uplink beam forming by the UE.

12. The UE of claim 8, in which the other instructions from the NodeB
comprise instructions on the number of MIMO streams to be used by the UE
in uplink MIMO transmissions.

13. The UE of claim 8, in which the dedicated downlink physical channel
is the WCDMA F-DPCH channel.

14. A method for operating a NodeB for a WCDMA system, the method
comprising transmitting instructions to a UE for the UE's uplink
transmissions, and transmitting said instructions on a dedicated downlink
physical channel which the NodeB is arranged to use for transmissions to
a plurality of UEs and which comprises a plurality of radio frames, with
each radio frame comprising a number of slots, each slot comprising a
number of WCDMA symbols, the method further comprising including in the
instructions to the UE Transmit Power Commands, TPC commands as well as
other instructions for the UE's uplink transmissions, the method further
comprising the use of a first WCDMA slot format for the TPC commands to
the UE and a second WCDMA slot format for the other instructions to the
UE.

15. The method of claim 14, comprising transmitting instructions to more
than one UE in one and the same WCDMA symbol.

16. The method of claim 14, comprising transmitting said other
instructions to a UE over several slots, using said second WCDMA slot
format.

17. The method of claim 14, comprising using said second WCDMA slot
format with a frequency which varies according to the UE's speed of
movement, so that the ratio between the number of slots with TPC and said
other instructions is varied adaptively with the UE's (120) speed of
movement.

18. The method of claim 14, according to which the other instructions to
a UE comprise instructions for uplink beam forming by the UE.

19. The method of claim 14, according to which the other instructions to
a UE for the UE's uplink transmissions comprise instructions on the
number of MIMO streams to be used by the UE in uplink MIMO transmissions.

20. A method for operating a UE for a WCDMA system, comprising receiving
instructions from a NodeB for uplink transmissions, the instructions
comprising Transmit Power Commands, TPC commands as well as other
instructions for uplink transmissions, and receiving the instructions on
a dedicated downlink physical channel which is used by the NodeB for
transmissions to a plurality of UEs and which comprises a plurality of
radio frames, with each radio frame comprising a number of slots, each
slot comprising a number of WCDMA symbols, the method comprising using a
certain slot format to interpret a received slot, the method comprising
using a first WCDMA slot format to locate TPC commands and a second WCDMA
slot format to locate the other instructions.

21. The method of claim 20, comprising receiving instructions which
comprise less than an entire WCDMA symbol.

22. The method of claim 20, comprising receiving said other instructions
over several slots, using said second WCDMA slot format.

23. The method of claim 20, according to which the other instructions
from the NodeB comprise instructions for uplink beam forming by the UE.

24. The method of claim 20, according to which the other instructions
from the NodeB comprise instructions on the number of MIMO streams to be
used by the UE in uplink MIMO transmissions.

25. The method of claim 20, according to which the dedicated downlink
physical channel is the WCDMA F-DPCH channel.

Description:

TECHNICAL FIELD

[0001] The present invention discloses devices and methods for
instructions for uplink transmission in a WCDMA system.

BACKGROUND

[0002] In so called closed loop WCDMA systems, instructions to a UE
regarding the UE's uplink transmission are transmitted to the UE from the
NodeB, although the instructions may in some cases originate from the
RNC.

[0003] The instructions for uplink transmissions may relate to, for
example, the number of streams to be used in uplink MIMO transmissions or
uplink beam forming transmissions. The beam forming case will be
described briefly below, which is for the sake of clarity only, and is
not intended to exclude the MIMO case.

[0004] Beam forming in transmissions from a UE can be seen as multiplying
the transmit signal at each antenna or antenna port (a notion which will
be explained in more detail later in this text) with a certain weight
factor, where the weight factor can be either complex or non-complex. For
a UE with more than one antenna or antenna port, this can be seen as a
pre-coding vector comprising the pre-coding factors to be used by the UE,
where the size of the pre-coding vector corresponds to the number of
antennas or antenna ports.

[0005] In closed-loop beam forming, the desired pre-coding vector is
determined by the NodeB and then signaled to the UE. Usually, a
pre-coding vector is signaled to a UE by means of signaling a code word
from a code book which comprises a number of such code words, where each
code word corresponds to a certain pre-coding vector in the code book.

[0006] With such downlink signaling to the UE, it will be realized that in
general, there will be a trade-off between signalling overhead and UE
performance. The higher granularity that is available for the pre-coding
weights (i.e. the larger the codebook), the more efficiently the NodeB
can adapt to the effective channel. On the other hand, a large codebook
that consists of many code words will result in an increased amount of
downlink feedback overhead, since, in general, the NodeB needs to be able
to signal all unique code words to the UE, and the number of bits
required to signal all code words in a codebook of size K is log2 K.

[0007] In order to keep track of the fast variations of the wireless
channel (e.g. fast fading) the pre-coding weights need to be updated
frequently, typically on a per slot basis. A WCDMA channel with a
structure that is suitable for carrying the pre-coding weight selection
instructions, i.e. the code words mentioned above, is the fractional
DPCH, the F-DPCH channel.

SUMMARY

[0008] It is an object of the invention to enable efficient signaling of
instructions to an UE for its uplink transmissions from a WCDMA NodeB on
a downlink channel with a structure similar to that of the WCDMA F-DPCH
channel.

[0009] This object is obtained by means of a NodeB for a WCDMA system
which is arranged to transmit instructions to a UE for the UE's uplink
transmissions. The NodeB is arranged to transmit said instructions on a
dedicated downlink physical channel which the NodeB is arranged to use
for transmissions to a plurality of UEs. The dedicated downlink physical
channel comprises a plurality of radio frames, and each radio frame
comprises a number of slots, with each slot comprising a number of WCDMA
symbols. The instructions to the UE comprise Transmit Power Commands, TPC
commands, as well as other instructions to the UE for the UE's uplink
transmissions. The NodeB is arranged to use a first WCDMA slot format for
the TPC commands to the UE and a second WCDMA slot format for the other
instructions to the UE.

[0010] In embodiments, the NodeB is arranged to transmit instructions to
more than one UE in one and the same WCDMA symbol.

[0011] In embodiments, the NodeB is arranged to transmit the other
instructions to a UE over several slots, using the second WCDMA slot
format.

[0012] In embodiments, the NodeB is arranged to use the second WCDMA slot
format with a frequency which varies according to the UE's speed of
movement, so that the ratio between the number of slots with TPC and the
other instructions vary adaptively with the UE's speed of movement.

[0013] In embodiments of the NodeB, the other instructions to a UE
comprise instructions for uplink beam forming by the UE.

[0014] In embodiments of the NodeB, the other instructions to a UE
comprise instructions on the number of MIMO streams to be used by the UE
in uplink MIMO transmissions.

[0015] In embodiments of the NodeB, the dedicated downlink physical
channel is the WCDMA F-DPCH channel.

[0016] The invention also discloses a UE for a WCDMA system, which is
arranged to receive instructions from a NodeB for uplink transmissions.
The UE is arranged to receive the instructions from the NodeB on a
dedicated downlink physical channel which is used by the NodeB for
transmissions to a plurality of UEs and which comprises a plurality of
radio frames, with each radio frame comprising a number of slots, each
slot comprising a number of WCDMA symbols. The UE is arranged to use a
certain slot format to interpret a slot, and the instructions from the
NodeB comprise Transmit Power Commands, TPC commands as well as other
instructions for uplink transmissions. The UE is arranged to use a first
WCDMA slot format to locate TPC commands and a second WCDMA slot format
to locate the other instructions.

[0017] In embodiments, the UE is arranged to receive instructions which
comprise a part of a WCDMA symbol.

[0018] In embodiments, the UE is arranged to receive the other
instructions over several slots, using the second WCDMA slot format.

[0019] In embodiments of the UE, the other instructions from the NodeB
comprise instructions for uplink beam forming by the UE.

[0020] In embodiments of the UE, the other instructions from the NodeB
comprise instructions on the number of MIMO streams to be used by the UE
in uplink MIMO transmissions.

[0021] In embodiments of the UE, the dedicated downlink physical channel
is the WCDMA F-DPCH channel.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The invention will be described in more detail in the following,
with reference to the appended drawings, in which

[0032] Embodiments of the present invention will be described more fully
hereinafter with reference to the accompanying drawings, in which
embodiments of the invention are shown. The invention may, however, be
embodied in many different forms and should not be construed as being
limited to the embodiments set forth herein. Like numbers in the drawings
refer to like elements throughout.

[0033] The terminology used herein is for the purpose of describing
particular embodiments only, and is not intended to limit the invention.

[0034]FIG. 1 shows a schematic overview of a part of a WCDMA system 100.
The WCDMA system comprises a number of cells, one of which is shown as
115 in FIG. 1. Each cell can accommodate a number of User Equipments,
UEs, one of which is shown as 120 in FIG. 1.

[0035] For each cell in the system, there will be a NodeB, shown as 115 in
FIG. 1, as well as a Radio network Controller, an RNC, shown as 105 in
FIG. 1.

[0036] As shown symbolically in FIG. 1, the UE 120 can be equipped with
more than one transmit antenna. As an example, the UE 120 is equipped
with two antennas, 121 and 122, although the number of antennas can also
be greater than two. Usually, each antenna will be a combined receive and
transmit antenna.

[0037] If a UE is equipped with two or more antennas, this fact can be
exploited in a number of ways, for example by letting the UE perform so
called beam forming in its uplink transmissions to the NodeB (as well as
in its reception of transmissions from the NodeB), or for so called MIMO
(Multiple Input Multiple Output) transmissions. A brief description will
be given below of beam forming, since beam forming by the UE as
instructed from the NodeB is one of the areas in which the invention can
be used.

[0038] As touched upon previously in this text, beam forming comprises
multiplying the transmit signal with a set of complex weight factors,
where one weight factor is used for each antenna port. The term "antenna
port" is used here rather than "antenna" or "physical antenna": in some
embodiments, each antenna port corresponds to a separate physical
transmit antenna. An example of beam forming in such an embodiment (i.e.
each antenna port is a physical antenna) is shown in FIG. 2: N transmit
antennas shown as a1-aN are used to transmit a signal s(t). The
signal s(t) is multiplied with a complex weight factor i=1-N, before
reaching antenna ai, which is done for each of the antennas
a1-aN.

[0039] This can also be seen as using a weight vector w which comprises
the weight factors w1-wN. The weight vector w is usually
referred to as a pre-coding vector. If a corresponding vector y is used
to refer to the signal which is transmitted from the N antenna ports,
i.e. y=[y1-yN], then the transmission can be written as y=w*s.

[0040] As shown in FIG. 2, from each transmit antenna ak there is one
stream received by each receiver antenna b1, i.e. stream hk,l
from transmit antenna ak is received by receiver antenna bl,
where k ranges from 1 to N and l ranges from 1 to M.

[0041] The transmitted signal y is received at the NodeB by M receive
antennas, shown as b1-bM in FIG. 2, and, as shown, the NodeB
also comprises a combiner for constructing the signal s(t) properly from
the signal y.

[0042] Thus, in the embodiment of FIG. 2, each antenna port corresponds to
a separate physical transmit antenna. In other embodiments, one of which
is shown in FIG. 3, an antenna port corresponds to a particular set of
antenna weights for all or a subset of the transmit antennas. In such a
case, different antenna ports correspond to different sets of antenna
weights and a signal that is transmitted through one antenna port is
transmitted through multiple antennas. FIG. 3 illustrates how K antenna
ports are mapped to N transmit antennas by the use of antenna weights
vnk where k and n denote the antenna port and transmit antenna
index, respectively. As shown in FIG. 3, the input signal s(t) is
pre-coded with weights w_1*s(t) to w_K*s(t) before being input to the
respective antenna port 1-K.

[0043] The output signal from the antennas a1-aN is in FIG. 3
shown as being received by M receiver antennas which are connected to a
combiner similar to the one of FIG. 2.

[0044] As mentioned, in embodiments of the invention, beam forming
instructions and/or MIMO instructions are conveyed from the NodeB to the
UE. When it comes to the beam forming instructions which are conveyed,
they are usually instructions regarding the pre-coding weights or,
rather, on pre-coding vectors to be uses by the UE. The information is
usually conveyed as so called code words, each of which identifies a
pre-coding vector in a particular code book which has also been
identified to the UE. As an example, the information would be conveyed as
"code word x from code book y".

[0045] A suitable channel structure offered for conveying beam forming
instructions or MIMO instruction to UEs from the NodeB 110 is the channel
structure offered by the WCDMA F-DPCH channel. One known use of the
F-DPCH channel is to transmit TPC commands, i.e. Transmit Power Control
commands, to the UEs. The F-DPCH channel uses spreading factor 256 and
QPSK modulation, and has a frame structure which is shown in FIG. 4:
frames with a length of 10 ms are split into 15 slots, where each slot
consists of 2560 chips. Each slot contains 10 symbols, where each symbol
consists of 2 bits. Every symbol corresponds to one TPC command, so that
a symbol with bit sequence 11 represents TPC command UP and a symbol with
bit sequence 00 represents TPC command DOWN. Consequently, every slot can
carry up to 10 TPC commands, and one F-DPCH channel can accommodate up to
10 UEs.

[0046] In order for a UE to find "its" information in a slot, the F-DPCH
uses so called slot formats which are numbered, a notion which will be
explained in more detail later in this text, but in order to obtain
proper operation, a UE and its NodeB need to know the slot format number
for the UE

[0047] The NodeB 110 of the invention is arranged to transmit instructions
to a UE such as the UE 120 on the WCDMA F-DPCH channel or on a channel
with the structure of the WCDMA F-DPCH channel for the UE's uplink
transmissions. The term "the structure of the WCDMA F-DPCH channel" here
refers to a channel which is a dedicated downlink physical channel which
the NodeB is arranged to use for transmissions to a plurality of UEs and
which comprises a plurality of radio frames, with each radio frame
comprising a number of slots, each slot comprising a number of WCDMA
symbols.

[0048] The instructions from the NodeB 110 to the UE 120 comprise TPC
commands, as well as other instructions, such as beam forming
instructions and/or MIMO instructions, to the UE 120 for the UE's uplink
transmissions. Assume now that a certain number of bits in a slot are
associated with the UE 120 by the NodeB 110: the NodeB 110 will then use
two of those bits for the TPC commands to the UE 120 and the remaining
bits for other instructions to the UE 120, such as, for example, beam
forming instructions and/or MIMO instructions. This is done by means of
simultaneously using multiple (two or more) F-DPCH slot formats to a UE,
so that one slot format is used for transmitting the TPC commands to the
UE and one or more other slot formats are used for transmitting the other
instructions to the UE.

[0049] The NodeB 110 is also, in embodiments, arranged to transmit
instructions to more than one UE in one and the same symbol, i.e. to
transmit an uneven number of bits in a slot to the UE 120. In such a
case, more than one UE could share information in one and the same F-DPCH
symbol, so that the number of UEs sharing information in an F-DPCH symbol
could, in fact, be equal to the number of bits in an F-DPCH symbol.

[0050] Thus, in embodiments, the NodeB 110 is arranged to let two or more
UEs share information in one and the same F-DPCH symbol, and in some such
embodiments to let a UE get an uneven number of bits larger where the
uneven number is large than one, by means of transmitting instructions to
one and the same UE using multiple WCDMA F-DPCH slot formats. For
example, instructions to the UE 120 would be conveyed with slot formats
1, 2 and 3, where slot format 1 is used to carry TPC commands and slot
formats 2 and 3 are used to carry beam forming and/or MIMO instructions,
where slot format 2 is shared between the UE 120 and another UE. This
could be implemented by letting the TPC bits in slot formats 2 and 3 be
re-interpreted as beam forming and/or MIMO instructions.

[0051] Thus, a UE can use more than 2 slot formats for reception if more
bits are needed for the instructions from the NodeB. With each additional
slot format, two additional bits will become available for signaling the
instructions. As mentioned above, there is also the possibility of
sharing a symbol between UEs, so that one of the bits in the symbol is
associated with one UE, and the other with another UE. Obviously, the
more slot formats (more symbols) a specific UE is allocated, the fewer
UEs can be multiplexed on a single F-DPCH, but in order to counter this,
if needed, the network can configure more than one F-DPCH.

[0052] Regarding the exact details when it comes to mapping the
instructions from the NodeB 110 to the UE 120 and other UEs to F-DPCH
symbols in one slot, the NodeB 110 is, in embodiments, arranged to use
one or more of the following principles:

[0053] Depending on how much beam forming/MIMO instructions that is needed
(i.e. the number of bits), then, as mentioned, one or more F-DPCH slot
formats can be allocated for a specific UE. Which bits or F-DPCH slot
formats that would correspond to TPC commands and which bits or F-DPCH
slot formats that would correspond to beam forming/MIMO instructions
would then be conveyed to the UE (and the NodeB(s)) via lub and RRC
signaling upon configuration. A mechanism to keep track of the use of
bits and/or slot formats is needed. As an example, assume that F-DPCH
slot formats 1, 3 and 5 are allocated to the UE 120. The TPC information
to the UE 120 could then be associated with slot format 1, and beam
forming/MIMO instructions would be associated with slot formats 3 and 5.
In such a case, four bits become available to convey beam forming/MIMO
instructions. Of the four bits, bit 1 and 2 could, as an example, be
conveyed using slot format 3 and bits 3 and 4 could be conveyed using
slot format 5.

[0054] In one embodiment where the NodeB uses multiple slot formats for
one and the same UE, the NodeB 110 is arranged to always use a certain
slot format number, for example the lowest slot format number, to convey
TPC commands to the UE 120, whereas the remaining slot formats are used
for conveying beam forming/MIMO instructions, where the significance of
the bits depends on the slot format number. If one always allocates
consecutive slot formats, this means that the NodeB 110 only needs to
signal the first slot format number and the total number of slot formats.

[0055] To simplify the reception of the F-DPCH channel, it is beneficial
for beam forming and/or MIMO capable UEs if the F-DPCH slot formats
allocated to a particular UE are consecutive. UEs which are capable of
beam forming and/or MIMO will moreover "consume" multiple F-DPCH slot
formats, while "legacy" UEs (i.e. UEs not capable of beam forming or
MIMO) will only consume a single F-DPCH slot format each.

[0056] If the allocation of F-DPCH slot formats does not distinguish
between UEs configured for beam forming and/or MIMO mode and legacy UEs,
this can lead to F-DPCH resource fragmentation. This is illustrated in
FIG. 5, which shows a sequence at times t0 and t0+Δ: at
time t0, the slot formats are allocated consecutively to UEs, i.e.
the first slot formats are allocated to UE1, then to UE 2 etc. At time
t0+Δ, UEs 2 and 5 (which are legacy UEs, and thus only need
one slot format each) have, in this example, left the system, and a new
UE capable of beam forming and/or MIMO, UE8, has arrived in the system.

[0057] Since UE8 needs two slot formats, it is allocated the slot formats
previously allocated to UEs 2 and 5, which leads to a fragmentation of
the slot formats for UE 8. In order to avoid this resource fragmentation
problem, the NodeB 110 is in embodiments arranged to allocate F-DPCH slot
formats to beam forming/MIMO capable UEs in ascending order, starting
with slot format 1, while "legacy" UEs instead are allocated F-DPCH slot
formats in descending order. This is illustrated in FIG. 6, which shows
that at time t0, UEs 1, 4 and 7 (which are UEs capable of beam
forming and/or MIMO) are allocated two slot formats each, starting from
slot format 1, and "legacy" UEs 5, 6, 3 and 2 are allocated one slot
format each. At time t0+Δ, the beam forming/MIMO capable UE 8
has arrived and legacy UEs UE2 and 5 have departed, and the UEs are now
assigned their slot formats in the order mentioned, i.e. beam
forming/MIMO capable UEs (i.e. UEs 1, 4, 7, 8) in ascending order,
starting with slot format 1, while "legacy" UEs (i.e. UE 3 and 6) are
instead allocated F-DPCH slot formats in descending order.

[0058] In embodiments, the NodeB is arranged to convey its instructions
(TPC, beam forming/MIMO/etc) to an UE in a TDM (Time Division Multiplex)
fashion using one (or several) F-DPCHs. In such embodiments, the NodeB
lets the F-DPCH in some slots carry TPC commands, and in other slots the
F-DPCH carries beam forming/MIMO related information. The ratio between
the number of slots with TPC commands and the number of slots with beam
forming/MIMO information can be fix, semi-static (RRC configured) or
dynamic and decided by the Node-B For example, beam forming/MIMO
information could be transmitted every xth slot, where x is equal or
larger than 2, and in the rest of the slots, TPC commands are
transmitted. Both the NodeB and the UE need to agree on the exact
transmission pattern to use, i.e. which slots that carry TPC commands and
which slots that carry beam forming/MIMO information.

[0059] Using one F-DPCH symbol (i.e. a certain slot format number) to
carry the instructions from the NodeB 110 to the UE 120 means that there
are two bits available for the instructions. If this is not enough, more
symbols can be used, e.g. by allocating more slot formats to an UE, as
described previously or by utilizing more than two of the twenty bits in
a slot for TPC and/or MIMO information to a UE. In embodiments, bits are
accumulated over several slots (still using one slot format) for beam
forming/MIMO instructions. In such embodiments, only one slot format
needs to be allocated per UE. Also, in such embodiments, the total number
of bits to be conveyed to a UE for beam forming/MIMO instructions could
be fixed (dependent on the codebook size), or it could vary depending on
the likelihood of the code words being used. One variant of the latter
approach is what is commonly referred to as Huffman coding, where likely
events are coded using few bits and less likely events are coded using
more bits. As an example of the approach with fixed number of bits,
consider a case where the NodeB needs four bits to convey the beam
forming/MIMO instructions and TPC commands are transmitted every second
slot. This means that every fourth slot, the NodeB can update the beam
forming/MIMO instruction, since the NodeB needs two slots to transmit the
four bits of beam forming/MIMO instructions, and TPC information is
transmitted every second slot.

[0060] In embodiments, the ratio between the number of slots with TPC and
beam-forming feedback can vary dynamically. For example, a slowly moving
UE (for example a stationary Laptop user) does not need updates of the
TPC commands as often as a fast moving UE since the channel is changing
slowly (i.e. "long coherence time"). Hence, for a slowly moving UE the
NodeB 110 can use more slots to convey beam forming/MIMO instructions,
and fewer slots for TPC commands. A fast moving UE, on the other hand,
needs update of the TPC commands more often, and therefore many (or all)
of the F-DPCH slots will have to carry TPC commands. However, for fast
moving UEs, the potential gain from beam forming or MIMO is marginal
anyways, due to the rapidly changing channel. The ratio between the
number of slots with TPC and beam forming/MIMO used for a certain UE can
therefore be varied depending on which "movement mode" the UE is in, e.g.
whether the UE speed of movement is fast, slow or medium. This can be
determined by either the NodeB or the UE by means of, for example,
Doppler measurements. Which mode to use can be signaled by the NodeB, for
example using HS-SCCH orders.

[0061] In embodiments, the NodeB can also combine the TDM operation
described above with the "general" approach: The TDM operation described
above can also be applied to the general approach described above. For
example, the TPC commands using slot format A are always conveyed (every
slot), while the beam forming related feedback conveyed using slot format
B uses the TDM operation (which could depend on the mode, Huffman coding,
etc, as described above). Slot format B could also be shared between
users by TDM operation.

[0062] Up to this point, the beam forming instructions have mainly been
mentioned in a general sense. Suitably, these instructions are
standardized. In general, the number of bits needed to convey the beam
forming information could be either fixed or dynamic, depending on the
number of available codebooks and the number of code words in each
codebook. For example, it would be possible to have one codebook for
switched antenna operation (i.e. "use antenna 1 only" or "use antenna 2
only") using only 1 bit, and to have one or several codebooks for general
beam forming operation, using e.g. 4 feedback bits to identify several
code words in each code book.

[0063] In embodiments, the NodeB 110 is arranged to transmit more beam
forming/MIMO related information in symbols by means of using higher
order modulation. For example 16-QAM, 64-QAM or 8-PSK could be used. This
can be applied in any of the above mentioned embodiments, in order to add
additional instruction bits. The modulation order can depend on the
present radio channel conditions, and can thus vary with the channel
conditions, and could also vary depending on the codebook that is used.
The modulation to be used can be signaled using HS-SCCH orders, or L2- or
L3-signalling. One solution would be to map modulation constellation
points that are close to each other to pre-coding vectors that are
similar, so that errors in detection of the feedback symbol translates to
only small errors in pre-coding weights.

[0064] One example of such higher order modulation is to use an 8-PSK (or
BPSK, QPSK, 16-PSK, etc) symbol to indicate the phase for pre-coding,
where phase adjustments are used. Then, if the constellation point right
next to the correct one is detected, only a small phase error will be
applied by the pre-coder. Another solution is to make the feedback
symbol's phase and amplitude correspond directly to the relative or
absolute phase and amplitude that the pre-coder should apply to one or
more transmit antenna ports. Then the symbol would not necessarily need
to correspond to a specific modulation constellation but could be freely
constructed without phase and/or amplitude quantization.

[0065]FIG. 7 illustrates the notion of F-DPCH slot formats: each UE is
associated with a certain slot format which tells the UE how to interpret
the information in the slot. As an example, with reference to slot format
0 in FIG. 7, we see that slot format 0 tells the UE that the first two
bits in the slot are to be interpreted as NOFF1 bits, and the
following two bits are TPC bits, with the remaining 16 bits being
NOFF2 bits. As shown in FIG. 7, there are 20 bits per F-DPCH slot in
total.

[0066] A beam forming/MIMO capable UE which would need more than two bits
to convey TPC information and other information would then need to be
associated with more than two bits of an F-DPCH slot format. As discussed
above, one solution would be to associate more than one slot format to
such a UE, where one of these slot formats is used to carry TPC
information and the rest of the slot formats are used to carry other
instructions. The more bits that are needed for the other instructions,
the more slot formats would be required since each additional slot format
provides two more bits. Note also that as mentioned previously, a slot
format can be shared between two UEs if an odd number of feedback bits
are required.

[0067] Another solution is to introduce new slot formats which are
tailored for carrying the other instructions. For example, one slot
format could use only one of the slot's twenty bits bit for TPC/beam
forming/MIMO, whereas another slot format could use three of the slot's
twenty bits for TPC/beam forming/MIMO.

[0068]FIG. 8 shows an embodiment of a NodeB 110. The NodeB 110 is a NodeB
for a WCDMA system, and is equipped with a first 21 and a second 22
antenna, both of which are suitably used for transmission and reception.
It should be pointed out that although the UEs in the system are suitably
equipped with more than one antenna, the NodeB doesn't need to have more
than one antenna, although, if, for example MIMO operation is desired,
two or more antennas at the NodeB will enhance the NodeB's operation.

[0069] In addition to the antennas 21 and 22, the NodeB 110 comprises an
input and output interface unit, I/O interface unit 23, which handles the
NodeB's interface towards, for example, UEs, via the antennas 21 and 22,
as well, as for example, handling its interface towards other nodes in
the WCDMA system, such as the RNC or other NodeBs. Such interfaces may be
either radio interfaces or landline interfaces.

[0070] In addition, the NodeB 110 comprises a transmit unit, Tx Unit 26,
and a Receive Unit, Rx Unit 24, The NodeB 110 also comprises a Control
Unit 25, which receives transmissions from UEs via the I/O interface unit
23 and the Rx unit 24, and which also controls transmissions to UEs via
the transmit unit 26 and the I/O interface unit 23.

[0071] The control unit 25 is also the unit which controls which slot
format to use for transmissions to a UE, which is, for example, done in
the following manner: suitably, the control unit 25 comprises an
instruction unit 30, which assembles the instructions to the UEs. The
instructions are used by a slot format unit 28 in order to check which
slot format that should be used with the instructions, so that, for
example, if the slot format unit 28 sees that the instructions are TPC
commands, the slot format for such commands is chosen, and if the
instructions are beam forming instructions, the slot format or formats
for such commands is/are chosen.

[0072] Which slot format to use for a certain kind of instructions is for
example retrieved from a memory unit 27, which has a table of
instructions and their corresponding slot formats. The proper slot format
and the instructions as such are then sent to a slot format unit 29 in
the control unit 25, which formats the instructions properly, i.e.
according to the proper slot format, and then sees to it that the slot as
such is transmitted from the transmit unit 26.

[0073]FIG. 9 shows a flow chart of a method 90 for operating a NodeB such
as the one 110, i.e. a NodeB for a WCDMA system. As indicated in step 95,
the method 90 comprises transmitting instructions to a UE for the UE's
uplink transmissions, and transmitting those instructions on a dedicated
downlink physical channel which the NodeB is arranged to use for
transmissions to a plurality of UEs and which comprises a plurality of
radio frames, with each radio frame comprising a number of slots, each
slot comprising a number of WCDMA symbols.

[0074] As indicated in step 92, the method 90 further comprises including
in the instructions to the UE Transmit Power Commands, TPC commands as
well as other instructions for the UE's uplink transmissions, and, as
indicated in steps 93 and 94, the method 90 further comprises the use of
a first WCDMA slot format for the TPC commands to the UE and a second
WCDMA slot format for the other instructions to the UE.

[0075] In embodiments, the method 90 comprises transmitting instructions
to more than one UE in one and the same WCDMA symbol.

[0076] In embodiments, the method 90 comprises transmitting the other
instructions to a UE over several slots, using said second WCDMA slot
format.

[0077] In embodiments, the method 90 comprises using the second WCDMA slot
format with a frequency which varies according to the UE's speed of
movement, so that the ratio between the number of slots with TPC and the
other instructions is varied adaptively with the UE's speed of movement.

[0078] In embodiments, according to the method 90, the other instructions
to a UE comprise instructions for uplink beam forming by the UE.

[0079] In embodiments, according to the method 90, the other instructions
to a UE for the UE's uplink transmissions comprise instructions on the
number of MIMO streams to be used by the UE in uplink MIMO transmissions.

[0080]FIG. 10 shows an example of a block diagram of the UE 120: the UE
120 comprises, as was also shown in FIG. 1, two antennas 111 and 112,
which are suitably both transmit and receive antennas. In addition, there
is a transmit unit, Tx unit 16, and a Receive Unit, Rx Unit 14, which are
connected to the two antennas via of an antenna network 13. The UE 120
also comprises a Control Unit 15 which receives transmissions from the
NodeB via the antennas 111 and 112 and the Rx unit 14, and which also
controls transmissions to the NodeB via the transmit unit 16 and the
antennas 111 and 112.

[0081] The control unit 15 thus receives TPC instructions and other
instructions from the NodeB, where the other instructions are, for
example, instructions regarding beam forming or MIMO. When a slot is
received, the control unit 15 addresses a memory unit 17 in order to find
out if and how the slot should be interpreted, i.e. if the slot should be
ignored or if it should be interpreted according to a certain slot
format, and if the slot contains TPC commands or other instructions, e.g.
MIMO or beam forming instructions.

[0082]FIG. 11 shows a flow chart of a method 200 for operating a UE such
as the one 120, i.e. a UE for a WCDMA system. As indicated in step 201,
the method 200 comprises receiving instructions from a NodeB for uplink
transmissions, comprising Transmit Power Commands, TPC commands, as well
as other instructions for uplink transmissions, and receiving the
instructions on a dedicated downlink physical channel which is used by
the NodeB for transmissions to a plurality of UEs and which comprises a
plurality of radio frames, with each radio frame comprising a number of
slots, each slot comprising a number of WCDMA symbols.

[0083] As indicated in step 203, the method 200 comprises using a certain
slot format to interpret a received slot, and, as indicated in steps 205
and 207, the method 200 comprises using a first WCDMA slot format to
locate TPC commands and a second WCDMA slot format to locate the other
instructions.

[0084] In embodiments, as indicated in step 209, the method 200 comprises
receiving instructions which comprise less than an entire WCDMA symbol.

[0085] In embodiments, as indicated in step 211, the method 200 comprises
receiving said other instructions over several slots, using said second
WCDMA slot format.

[0086] According to embodiments of the method 200, the other instructions
from the NodeB comprise instructions for uplink beam forming by the UE.

[0087] According to embodiments of the method 200, the other instructions
from the NodeB comprise instructions on the number of MIMO streams to be
used by the UE in uplink MIMO transmissions.

[0088] In embodiments of the method 200, the dedicated downlink physical
channel is the WCDMA F-DPCH channel.

[0089] In the drawings and specification, there have been disclosed
exemplary embodiments of the invention. However, many variations and
modifications can be made to these embodiments without substantially
departing from the principles of the present invention. Accordingly,
although specific terms are employed, they are used in a generic and
descriptive sense only and not for purposes of limitation.

[0090] Embodiments of the invention are described with reference to the
drawings, such as block diagrams and/or flowcharts. In some
implementations, the functions or steps noted in the blocks may occur out
of the order noted in the operational illustrations. For example, two
blocks shown in succession may in fact be executed substantially
concurrently or the blocks may sometimes be executed in the reverse
order, depending upon the functionality/acts involved.

[0091] It is understood that several blocks of the block diagrams and/or
flowchart illustrations, and combinations of blocks in the block diagrams
and/or flowchart illustrations, can be implemented by computer program
instructions. Such computer program instructions may be provided to a
processor of a general purpose computer, a special purpose computer
and/or other programmable data processing apparatus to produce a machine,
such that the instructions, which execute via the processor of the
computer and/or other programmable data processing apparatus, create
means for implementing the functions/acts specified in the block diagrams
and/or flowchart block or blocks.

[0092] These computer program instructions may also be stored in a
computer-readable memory that can direct a computer or other programmable
data processing apparatus to function in a particular manner, such that
the instructions stored in the computer-readable memory produce an
article of manufacture including instructions which implement the
function/act specified in the block diagrams and/or flowchart block or
blocks.

[0093] The computer program instructions may also be loaded onto a
computer or other programmable data processing apparatus to cause a
series of operational steps to be performed on the computer or other
programmable apparatus to produce a computer-implemented process such
that the instructions which execute on the computer or other programmable
apparatus provide steps for implementing the functions/acts specified in
the block diagrams and/or flowchart block or blocks.